Previously this laboratory reported that various microanalytic methods detected different levels of fluoride in aliquots of plasma from the same sample. Currently we are assessing fluoride levels in monkey dental plaque: (1) aliquots of pooled dental plaque; (2) samples from maxillary and mandibular teeth collected over several weeks. Both the heat mediated and silane mediated methods detected similar levels of fluoride. The fluoride appeared to be unevenly distributed in dental plaque and varied in amount from week to week.